The value of diffusion-weighted imaging based on monoexponential and biexponential models for the diagnosis of benign and malignant lung nodules and masses.

Objectives: The objective is to compare the efficacy of diffusion-weighted imaging (DWI) parameters of mean and minimum apparent diffusion coefficient (ADC and ADC) and intravoxel incoherent motion (IVIM) in the differentiation of benign and malignant lung nodules and masses.

Methods: Lung lesions measured larger than 1.5 cm on CT were included between August 2015 and September 2018. DWI (10 b-values, 0-1000 s/mm) scans were performed, and the data were post-processed to derive the ADC, ADC and IVIM parameters of true diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f). An independent sample -test or Mann-Whitney test was used to compare benign and malignant parameters. Receiver operating characteristic curves were generated and a test was used.

Results: 121 patients were finally enrolled, each with one lesion. Examined 121 lesions were malignant in 88 (72.7%) and benign in 33 (27.3%). The ADC of malignant pulmonary nodules was significantly lower than that of benign pulmonary nodules ( = 3.156, = 0.006), whereas the other parameters revealed no significant differences ( = 0.162-0.690). Receiver operating characteristic curve analysis revealed that an ADC threshold value of 1.43 × 10 mm/s yielded 88.57% sensitivity and 64.29% specificity. While for lung masses, the ADC, ADC, D and D* values in malignant pulmonary masses were significantly lower (﹤0.001-0.011). Among them, the D value exhibited the best diagnostic performance when the threshold of D was 1.23 × 10mm/s, which yielded a sensitivity of 90.57% and a specificity of 89.47% ( = 2.230, 3.958, 2.877 and = 0.026, ﹤0.001 and 0.004, respectively).

Conclusion: ADC is the most robust parameter to differentiate benign and malignant lung nodules, whereas D is the most robust parameter to differentiate benign and malignant lung masses.

Advances In Knowledge: This is the first study to compare all the quantitative parameters of DWI and IVIM mentioned in the literatures for assessing lung lesions; Second, we divided the lesions into lung nodules and lung masses with the size of 3 cm as the boundary.